MiKlip first phase: MesoTel

MesoTel aims to improve the accuracy of atmospheric dynamics and of the deterministic forecast of seasonal means over Europe by taking into account the relevant feedback of the atmospheric meso-beta-scale dynamics on the large to planetary scales and vice versa in the climate system on the northern hemisphere.In particular, the relevance of the meso-beta-scale atmospheric dynamics for the development of extremely growing Rossby wave trains affecting the ocean dynamics and the mean atmospheric flow shall be investigated and a contribution to our understanding of the mechanisms determining the interannual to decadal predictability shall be made. Hereto a two-way coupled model system consisting of the atmosphere-ocean general circulation model ECHAM/MPIOM and of the regional climate model COSMO-CLM shall be developed. The COSMO-CLM is a model system for operational numerical weather prediction and regional climate modelling designed for the meso-beta scales down to approx. 1km. The ECHAM/MPIOM is designed for simulation of the large to meso-scale climate dynamics down to resolutions of the atmosphere of approx. 50km. In the two-way coupling mode all prognostic model variables (primitive equation variables and humidity components) will be exchanged between the independent models after each ECHAM time step. In this way the ECHAM/MPIOM solution is modified continuously within the COSMO-CLM simulation domain.

Figure 1: Annual Precipitation 1961-1990 (ERA40), locations (black symbols) of first four DJF singular vectors of a barotropic model of 40 NCEP 300 hPa seasonal mean flows at the development times up to 96 h and simulation domains of the limited area model (red boxes).

The region of Central America (TEL1) (see Figure 1) is one of the two regions of frequent development of Rossby wave trains (RWTs) in the northern hemisphere. The RWTs developing in this region cross the Atlantic and directly affect the European weather and climate. The high-resolution simulation of this region has the potential to improve the simulation of the development of the RWTs and of their hypothesized interplay with SSTs and with the mean flow. Finally, the interplay of these processes and their contribution to interannual predictability shall be analysed and an efficient model system configuration shall be developed.

Goals

Development of a two-way nested model version ECHAM/MPIOM with COSMO-CLM

Analysis of the relevance of the meso-scale dynamics for large scale dynamics over Europe

Improvement of the inter-annaul to decadal predictability of seasonal means for Europe